package Demo01;

public class Test {
    public static void main(String[] args) {

    }
}
class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode big = null, small = null;
        while(head!=null) {
            small = head.next;
            head.next = big;
            big = head;
            head = small;
        }
        return big;
    }
}
